The objective of this research proposal is to study the recurrence rate of bladder tumors in patients following correction of abnormal tryptophan metabolism. This investigation will concentrate on those tumor patients showing an abnormal urinary excretion pattern of tryptophan metabolites following an oral tryptophan load. Clinical trials will evaluate the effect of pyridoxine (vitamin B6) on recurrence rate of bladder tumors. The methods employed will be: 1) selection of patients with Grade O or A tumors; 2) analysis of 24-hour urinary tryptophan metabolites before and after the ingestion of L-tryptophan; and 3) clinical trials utilizing pyridoxine and placebo in a double-blind study. The purpose of the research is to elucidate the long-term recurrence rate of heterotopic bladder tumors in those patients whose abnormal tryptophan metabolism has been corrected.